A demand for a data transmission technology using multi-channels in order to increase a transmission rate has increased. In particular, the need of a transmission method simultaneously using a plurality of channel bandwidths positioned at different radio frequency (hereinafter, referred to as an RF) bands have come into the limelight. Examples using different radio frequency bands include orthogonal frequency division multiplexing (OFDM) inter-mode conversion by the Institute of Electrical and Electronics Engineers (IEEE) 802.11 series technology associated with a so-called wireless LAN (WLAN) or Wi-Fi and a cognitive radio (CR) communication using white spaces that exist in different RFs.
In the cognitive radio communication, a required channel bandwidth cannot be arbitrarily redesigned while a frequency plan is settled. Therefore, there is a limitation to compulsorily follow the existing frequency plan. However, since it is difficult to meet a desired transmission rate with a single channel bandwidth, a plurality of channel bandwidths positioned in different RFs are required to be used. An apparatus and a method for improving transmission performance by minimizing inter-carrier interference through adaptively controlling subcarrier spacing are required in an OFDM communication system.